Well, for the show to follow what the UK version did, Francis would've been killed in the last episode. I can't see that happening for a while. I can see the next season being about him beating Dunbar, then a lot of focus on beating the Republican candidate before he takes in office again. Should they do all that next season then I don't know how it'll end. Just him being President will get stale after a while so it must be inevitable that a key character (Francis) dies or the story finds a natural end. Kevin Spacey did say in an interview that they don't want to show to go on forever, so I bet it won't go on for more than 4-6 seasons max. A bit like Breaking Bad I guess.
I was happy to see Freddy making an appearance again. Very curious to see if Remy will be in the show next season. What if he gets together with Jackie? I wouldn't say it's impossible to Jackie to go back to Francis again, or atleast get in a serious relationship with Remy to build a side story now that Rachel is dead (she's hot - I'd totally do her).
This season was deffo a lot slower than the first 2 tho. I still enjoyed this one too but I sortof miss seeing Francis on a hunt for something, rather than sitting on top of the cake. Maybe with Claire leaving him, that'll spark some action to S4.
An alternative show ending could be Claire going to Dunbar, telling secrets, then going to Court and Francis loses the campaign as a broken man.